ME ::     Myalgic Encephalomyelitis

Below are itemised four definitions / criteria for G93.3 myalgic encephalomyelitis but not CFS. Although the CDC has separated ME and CFS, they do not seem to offer a definition for ME only CFS. The following four are the definitions / criteria are from authors of long standing and history in this field, for more information follow the links with each definition. 1. A.M.Ramsay, 2. Ramsay & Dowsett, 3. London Criteria, 4. Byron Hyde.

In "Redefinitions of ME/CFS - A 20th Century Phenomenon" Dr. E.G. Dowsett summarizes historic ME and CFS definitions and emphatically states, " To Summarise: I would urge all our colleagues to look again at the literature prior to 1988 before redefining this illness. Meantime, the Ramsay description of myalgic encephalomyelitis in 1986 with slight modifications to form a short definition still remains a useful guide to those new to this work:

The Ramsay Definition for Myalgic Encephalomyelitis

“A syndrome initiated by a virus infection, commonly in the form of a respiratory or gastrointestinal illness with significant headache, malaise and dizziness sometimes accompanied by lymphadenopathy or rash. Insidious or more dramatic onsets following neurological, cardiac or endocrine disability are also recognised. Characteristic features include:

  1. A multisystem disease, primarily neurological with variable involvement of liver, cardiac and skeletal muscle, lymphoid and endocrine organs.
  2. Neurological disturbance – an unpredictable state of central nervous system exhaustion following mental or physical exertion which may be delayed and require several days for recovery; an unique neuro-endocrine profile which differs from depression in that the hypothalamic/pituitary/adrenal response to stress is deficient; dysfunction of the autonomic and sensory nervous systems; cognitive problems.
  3. Musculo-skeletal dysfunction in a proportion of patients (related to sensory disturbance or to the late metabolic and auto immune effects of infection)
  4. A characteristically chronic relapsing course."
The full paper here


From "Myalgic Encephalomyelitis - Then and Now.  An Epidemiological Introduction"
(Chapter 7 in Clinical and Scientific Basis of M.E./CFS):


The illness, though similar to non-paralytic poliomyelitis in many clinical aspect, could clearly be distinguished and was diagnosed as Benign Myalgic Encephalomyelitis.  This name gives a clearer clinical description than many of the eponyms used previously (Iceland Disease, Akureyri's Disease, Epidemic Neuromyasthenia) or invented subsequently (Post viral syndrome, Chronic Fatigue Immune Dysfunction Syndrome).  These share the common disadvantage of obscuring the world-wide incidence or of trivializing the clinical severity of the illness."

Dr. Ramsay,together with Dr. Dowsett, listed this criteria for M.E. in 1990 in the same article (just prior to his death).

We adopted the following criteria:

A syndrome initiated by a viral infection commonly described as a respiratory/gastro intestinal illness but a gradual or more dramatic onset following neurological, cardiac or endocrine disability is recognised.

The cardinal features, in a patient who has previously been physically and mentally fit, with a good work record are:

  1. Generalised or localised muscle fatigue after minimal exertion with prolonged recovery time.
  2. Neurological disturbance, especially of cognitive, autonomic and sensory functions, often accompanied by marked emotional lability and sleep reversal.
  3. )Variable involvement of cardiac and other bodily systems.
  4. An extended relapsing course with a tendency to chronicity.
  5. Marked variability of symptoms both within and between episodes."


Version 2
EG Dowsett et al, 'London criteria for M.E.', Report from The National Task Force on Chronic Fatigue Syndrome (CFS), Post Viral Fatigue Syndrome (PVFS), Myalgic Encephalomyelitis (ME). Westcare, 1994, pp. 96-98.

These three criteria must all be present for a diagnosis of M.E./PVFS to be made. If any of these are not present the volunteer research subject should not be used for the purpose of research into M.E./PVFS and an alternative diagnosis should be keenly sought.

  • 1 Exercise-induced fatigue precipitated by trivially small exertion -physical or mental - relative to the patient's previous exercise tolerance.
  • 2 Impairment of short-term memory and loss of powers of concentration, usually coupled with other neurological and psychological disturbances such as emotional lability, nominal dysphasia, disturbed sleep patterns, dysequilibrium or tinnitus.
  • 3 Fluctuation of symptoms, usually precipitated by either physical or mental exercise (see b) above.
These symptoms should have been present for at least 6 months and should be ongoing.


Although M.E./PVFS typically follows an infection, usually a viral illness (which may be subsubclinicalal) in a previously fit and active person, it has also been observed to be triggered by other factors such as immunisations, traumas and exposure to chemicals. Furthermore, in a minority of patients, M.E./PVFS has a gradual onset with: no apparent triggering factor. For these reasons proof of a preceding viral illness is not a prerequisite for diagnosis or inclusion in a study group.

The more complete London Criteria Version 2 Myalgic Encephalomyelitis (ME)

Byron Hyde's new and simple definition of Myalgic Encephalomyelitis, a diagnosistic summary; Below is the more symptomatic summary From The Nightingale, Myalgic Encephalomyelitis Definition

Clinical Features

The clinical features of Myalgic Encephalomyelitis are consistent with the following characteristics that can easily be documented by the physician.
  1. M.E. is an acute onset biphasic epidemic or endemic (sporadic) infectious disease process: Both Epidemic and Non-Epidemic cases are often preceded by a series of repeated minor infections in a previously well patient that would suggest either a vulnerable immune system, or an immune system subject to overwhelming stressors such as:
    • repetitive contact with a large number of infectious persons,
    • unusually long hours of exhausting physical and / or intellectual work,
    • physical traumas,
    • immediate past immunizations, particularly if given when the patient has concurrent allergic or autoimmune or infectious disease or if the patient is leaving for a third world country within three weeks of receiving the immunization,
    • epidemic disease cases whose onset and periodicity appear to occur cyclically in a susceptible population,
    • the effect of travel, as in exposure to a new subset of virulent infections, or
    • the effects of starvation diets.
    (It should be noted that subsets c, d, e, f and g are all stressors associated with decreased immune adaptability plus an associated infection with an appropriate neurovascular infectious virus or other infectious agent. This may be due either to an immediate preexisting infectious disease or to a closely following infection, either of which may or may not be recognized.)
  2. Primary Infection Phase: The first phase is an epidemic or endemic (sporadic) infectious disease generally with an incubation period of 4 to 7 days; in most, but not all cases, an infection or infectious process is evident. (See Clinical and Scientific Basis of M.E./CFS, Chapter 13, pps. 124-126)
  3. Secondary Chronic Phase: The second and chronic phase follows closely on the first phase, usually within two to seven days; it is characterized by a measurable diffuse change in the function of the Central Nervous System. This second phase is the persisting disease that most characterizes M.E.
  4. The Presence or Absence of Various Pain Syndromes is highly variable: The pain syndromes associated with the acute and chronic phases of M.E. may be described as Early and Late findings.
    Early Findings:
    • severe headaches of a type never previously experienced;
    • these are often associated with neck rigidity and occipital pain;
    • retro-orbital eye pain;
    • migratory muscle and arthralgia pain;
    • cutaneous hypersensitivity.
      Late Findings: Any of the early findings plus
    • fibromyalgia-like pain syndromes.
    This is only a partial list of the multiple pain syndromes. Many of the pain features tend to decrease over time but can be activated or increased by a wide range of external & chemical stressors. (See Clinical and Scientific Basis of M.E./CFS, Chapter 5, pps. 58-62)

      The 2003 Canadian ME / CFS Case Definition,
Myalgic Encephalomyelitis / Chronic Fatigue Syndrome: Clinical Working Case Definition, Diagnostic and Treatment Protocols

"Fair Use" notice, if you wish to copy, reproduce or otherwise use material contained at this site; PLEASE READ.

Myalgic encephalomyelitis is a relapse-remitting disease with new symptoms occurring either in discrete relapses (or "crashes") or slowly accruing over time. Between relapses, symptoms may resolve completely with sufficient rest, but permanent neurologic problems often persist, especially as the disease advances.

Patients should learn to set boundaries, prioritise activities, and pace themselves without overdoing it on a `good day'. Otherwise they risk triggering a relapse of symptoms.

If it takes more than 30-60 minutes to recover from activity, then the patient is probably overdoing it.

When a condition/illness is labeled 'Postviral', one would assume that a preceding viral illness is a prerequisite for the diagnosis with the ICD-10 code of G93.3, where as without the signs of a preceding viral illness the condition is coded as ICD-10 code of R53.82.

"...The failure to agree on firm diagnostic criteria has distorted the data base for epidemiological and other research, thus denying recognition of the unique epidemiological pattern of myalgic encephalomyelitis."
-Dr. A. Melvin Ramsay-

sequela: A pathological condition resulting from a prior disease
Any abnormality following or resulting from a disease or injury or treatment
"paralysis is one of the sequelae of poliomyelitis"
encephalomyelitis - a sequela to - A ?, B ?, C ? etc

Avoid or manage aggravators or triggers: (e.g. overexertion, surgery, anaesthetics, vaccinations, chemicals, air travel) that may cause relapses. refs

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